Twin with hx35
 

What turbo should i run with a stock hx35

if your doing twins, ht3b, but i wouldnt recomend running the stock hx35, look into an hx40. the stock 12cm exhaust housing is way to restrictive when you start pushing some fuel, your egts will be threw the roof!

S472 and it just so happens that I have one for sale. If you use the 35 drill the wastegate divider.

would it help him out to put a bigger housing on the hx35?

It would help but wastegated 14cm housings get expensive.

I've seen suggestions that if you use the HX or HY35 that you should port the wastegate hole below the flapper to a larger orifice. I would think drilling the divider out to balance cylinder drive pressures when the gate opens would be a good idea also. I don't know much about tuning a set of twins, but I've seen where lowering the wastegate opening pressure or at least keeping the stock charger load low is ideal.